Hats of all types have typically been constructed with substantially circular lower rims which have traditionally been constructed in fixed sizes in increments of 1/8 of an inch diameter. The diameter measurement is for a fixed circular-shaped lower rim or headband, such that each 1/8 inch incremental head size corresponds to approximately 3/8 of an inch circumferential dimension (.pi..times.1/8.apprxeq.3/8). Metric sizes for hats are typically measured in centimeters of circumference, with each centimeter of circumference in increments of 1 centimeter for each hat size. This 1 cm metric measurement corresponds closely to each 1/8 inch hat size measurement as 3/8 inch circumference .apprxeq.1 cm circumference. Thus, for example, a size 7 hat is one with a circumference of approximately 22 inches, which is convertible to approximately 56 centimeters and thus, a size 56 under the metric system. Various manufacturers designate hat sizes as small, medium, large, extra large, or similar general designations. For example, under one system hat sizes were designated as "small," corresponding to standard hat size covering 63/4 and 67/8 (about 54 cm-55 cm); "medium," covering hat sizes 7 and 71/8 (about 60 cm-61 cm); "large," covering hat sizes 71/4 to 73/8 (about 58 cm-59 cm); and "extra large" covering hat sizes 71/2 to 75/8 (about 60 cm-61 cm). While the small, medium, large, and extra large designations did not normally provide a reliably good fit, the variations between 1/8 hat sizes (i.e., about 3/8 circumference or 1 centimeter circumference sizes) usually provided tolerably repeatable fits when accurately constructed. However, because of variations in actual size compared to the nominal size from one manufacturer to another or from one type of material to another, reliable hat fit was not always available.
In the area of sports caps of the type with sun visors or bills, which is typical of a baseball cap, the overall cost of manufacture did not normally justify the types of precision manufacturing required for reliably making caps in each of the 1/8 inch diameter (1 cm circumference) incremental sizes. Also, maintaining an inventory of caps in all the various size ranges was often cost-prohibitive. Even the generalized size ranges covered by "small," "medium," "large," and "extra large" designations with each size covering two sizes resulted in a total range of sizes from about 63/4 to 75/8. Obtaining better fit would have required an inventory of eight (8) separate sizes. Also, in view of the use of caps in sports events, not only by adults by also by youngsters, additional sizes were needed for youth sizes as small as size 63/8 (20 inches in circumference or metric size 51 centimeters) for youth and also for large athletic adult men as large as hat size 8 (251/4 inches in circumference or 64 centimeters in metric size). Covering this entire range could have required an inventory of fourteen (14) separate hat sizes.
In order to overcome some of the fitting problems or inventory problems, various types of adjustable caps have been devised. Adjustability has typically been accomplished by forming a cut-out portion or an open window, commonly referred to as an "open back" in the rear of the cap crown. The open back was bridged by an adjustable strap or other mechanism by which the size could be adjusted. For example, a pair of overlapping plastic straps, one formed with multiple, projecting plastic rivets, the other formed with multiple holes so that the hat size could be adjusted by interconnecting the appropriately located projecting rivets and holes. Such caps could be incrementally adjusted or readjusted for different users or for variations in head size which might be due to hair style changes of an individual. Often, the incremental adjustments available for multiple size caps resulted in a cap which was either too loose or too tight. Alternatively, the open back was provided with a short continuously adjustable belt, a short piece of elastic, or a hook and loop material which allowed continuous adjustment in a similar fashion as the overlapping plastic bands with releasable rivets. These arrangements with the adjustable open back hat portion helped to alleviate the inventory problems as just a few crown sizes with adjustable open backs could accommodate substantially the entire range of hat sizes. However, new problems with appearance and fit were created. Adjustment of such a cap to a small hat size produced a large amount of bunching of the crown material at the rear of the cap. The bunching produced an unsightly appearance, particularly at the rear of the hat, and also tended to deform the rounded appearance of the rest of the cap crown. Adjustment of such caps to a large hat size caused the crown material at the rear to be stretched or flattened. The flattening at the rear crown portion similarly also tended to result in a misshapen crown elsewhere. Further, the fit and the appearance were interfered with because the open back sometimes resulted in the wearer's hair sticking out of the window in an undesirable fashion.